Research @ Otago - Rebecca McMullin

Rebecca’s research focuses on tracking the flow and fate of waste materials from salmon farms through food webs in the Marlborough Sounds.

Salmon aquaculture involves the input of large quantities of feed into sea farms, which in turn results in the production of organic and nutrient wastes that have the effect of increasing the ecological footprints of the farm. This may have consequences for the connectivity of food webs within the farm's ecological footprint.
 

Bagging and labelling samples

With help from a team of researchers in the Department of Marine Science, Rebecca has collected key species of fish, macroinvertebrates and benthic infauna (small invertebrates that live in the sediment) from around salmon farms in the Marlborough Sounds. These samples are now being processed and analysed to determine the proportion of organic matter each organism sources from farm waste relative to the proportion they source from natural marine sources such as macroalgae and phytoplankton.

Collecting samples from a salmon farm in the Marlborough Sounds

Rebecca has also set up mesocosms (like miniature ecosystems) at Portobello Marine Laboratory that will allow us to measure parameters that are useful for modelling the real-world system in the Marlborough Sounds.

Mesocosm set up at the Portobello Marine Laboratory

Ultimately this research will be useful in minimising negative impacts of aquaculture on natural ecosystems.

Research @ Otago - Daniel Smart

Daniel’s research focuses on understanding one of the most pivotal aspects of an organism, its reproductive cycle, and how a warming ocean will affect the development of larvae. 

Daniel is working on the blue mussel (Mytilus galloprovincialis), a species in New Zealand for which there are large knowledge gaps. Trying to fill these knowledge gaps is of importance as blue mussels are significant organisms, having key roles in coastal marine ecosystems.

Daniel is investigating the timings of the reproductive cycle by taking monthly samples and looking at which stage they are at in their reproductive cycle. This will be carried out over a 12-month period, enabling an understanding of the timings of the reproductive cycle.   

Blue mussel open ready for dissection

Daniel is also looking at how blue mussel larvae will respond to a warming ocean, with experiments being run using different temperature treatments, and assessing the impacts of these different temperatures on the development and survival of the larvae.

Research @ Otago - Nadjejda Espinel

Nadjejda is studying the effects of climate change on marine ecosystems, and marine invertebrates in particular.   

Nadjejda raises the microscopic larvae in the laboratory

Nadjejda's research focuses on the effects of ocean acidification and warming on the larval settlement of some New Zealand key species including paua, kina, barnacles (Austrominius modestus) and polychaetes (Galeolaria hystrix), trying to understand how these species will fare in future acidified and warmed-up oceans.

The approximate size of the Nauplius larvae is 0.5mm

Most of the sessile  (organisms that live attached to the substrate) and benthic marine invertebrates spawn planktonic larvae into the water column. These larvae swim freely until they find a place appropriate to spend their adult lives and then they settle and metamorphose - this is what we call the settlement process. Any factors influencing the settlement process might influence the future distribution of species and ultimately the diversity of the marine ecosystems.  The settlement process could be influenced by direct changes in the larval physiology, or by indirect changes in the settlement substrates.

Nadjejda collecting adult barnacles from the rocks at Portobello Marine Laboratory

In order to study this, Nadjejda collects invertebrates (adults), spawns them and rears the larvae in the lab, in order to get them to settle. The core of her research comprises experiments in the lab trying to settle larvae in different pH treatments on different types of substrates, in order to see whether a significant effect can be expected at the future predicted levels of acidification and warming.